Effects of Circumferential Nonuniformity in Compressor Flow Fields Including Vane Wake Variability

摘要

Circumferential nonuniformity will always exist in a compressor flow field due to manufacturing inconsistencies,eccentricities, and slight inlet flow nonuniformities. Consequently, discrete stationary measurements can be skewedand contribute to uncertainty in calculated one-dimensional performance. Thus, this research characterizes vanewake variability in a three-stage axial compressor and explores the implications on efficiency calculations. Detailedcircumferential traverses with seven-element total pressure and total temperature rakes downstream of each vanerow were completed. Results show that wake width circumferential variability is more sensitive to spanwise locationthan wake depth variability. For this compressor with a pressure ratio of approximately 1.3 at peak efficiency, theobserved efficiency variations based on pressure and temperature variations are on the order of three points for theoverall compressor, but up to 15 points for individual stage efficiency. Additionally, vane wake variabilityimplications on rotor forced response are explored. Results show that the measured levels of wake variability lead tomore than a 60% difference in spectral magnitudes of the fundamental forcing frequency. Thus, the error associatedwith the difference between the measured wake and average wake should be considered when comparingmeasurements to computational results which often assume perfectly periodic geometry and uniform inlet conditions.